I found the solution. This is because Google Chrome for Android no longer supports Adobe flash, even though Chrome desktop does. You just have to use a different browser on your phone to see the videos.

Use Firefox or Dolphin browser, click on the video, then you'll be prompted to download the Adobe flash player app. You'll need to enable apps from unknown sources, then install the app. Once finished navigate back to the video and it will play.

and some rin up hill and down dale, knapping the chucky stanes to pieces wi' hammers, like sae mony road-makers run daft - they say it is to see how the warld was made!